1. Field of the Invention
The present invention relates to a recording tape cartridge that accommodates, inside a casing, recording tape such as magnetic tape that is used as a recording and playback medium mainly for devices such as computers.
2. Description of the Related Art
Conventional recording tape cartridges are known where recording tape of magnetic tape and the like used as data recording/playback media primarily for computers is wound around a single reel, which is accommodated inside a casing. These types of recording tape cartridges are equipped with braking means that stop the reel from rotating inside the casing when the cartridge is not in use.
To be more specific, the reel is provided with a cylindrical reel hub having a bottom, and a brake component that serves as the braking means inside the reel hub is provided so as to be both non-rotatable relative to the casing and biased downwards. The brake component is made from a resin material and a brake gear is formed on the bottom surface thereof. This brake gear meshes with an engaging gear formed inside the reel hub, whereby rotation of the reel is blocked.
Further, a releasing component, which appears triangular when viewed as a flat surface and which is formed from a resin material, is provided between the bottom wall of the reel hub and the brake component. The center of the top surface of the releasing component abuts the center of the bottom surface of the brake component. Leg portions are provided so as to protrude from each tip portion of this releasing component. These leg portions are inserted through through-holes provided on a reel gear and they protrude at preset heights from the bottom surface of the bottom wall of the reel hub.
Accordingly, when the recording tape cartridge is loaded into a drive device, the brake component is pressed upwards via the releasing component (i.e., the leg portions) with the action of a drive gear formed on the rotation shaft of the drive device meshing with the reel gear, whereby meshing of the brake gear relative to the engaging gear is released. Due to this, the reel is allowed to rotate and the releasing component rotates with the reel. (See, for example, the Official Gazette of Japanese Patent Application Laid-Open (JP-A) No. 11-353850.)
In a recording tape cartridge configured in this manner, the through-holes provided on the reel gear are generally circular and are formed to be rectangular longer in the circumferential direction. Accordingly, the shapes of the leg portions of the releasing component are also either formed into cylindrical or quadrangular shapes. When the leg portions of the releasing component are quadrangular shapes, a set of boxes is used to form them, and this is disadvantageous in that metal mold processing is not easy and burrs are likely to form in the formed components.
In contrast, when the leg portions of the releasing component are made in cylindrical shapes, it is not necessary to use a set of boxes to form them so metal mold processing is easier. Further, there is an advantage when forming with a metal mold in that the flowing attributes (i.e., forming characteristics) of the resin material flowing towards the external side from the central portion in contact with the brake component are also better. Nonetheless, this is still problematic in that the sizes of the leg portions are larger than when the leg portions are formed into quadrangular shapes.
With recent recording tape cartridges, a problem has arisen with the ever-increasing drive for high-capacity recording, specifically in the rigidity of the reel hubs around which the recording tape is wound (i.e., collapsing deformation of the reel hub occurs). In response, measures have been considered in which the thickness of the reel hub is increased. When increasing the thickness of the reel hub, the inner side (i.e., towards the center of the reel hub) is thickened in order to ensure that the needed capacity can be provided. However, in the case of a recording tape cartridge having a releasing component, there is a limit to how much the reel hub can be thickened when the through-holes through which the leg portions are inserted are circular.